CN1225725C - Ferromagnetic stack material with reliable uniaxial anisotropy - Google Patents

Abstract

A magnetoresistive film includes a pinned ferromagnetic layer; a free ferromagnetic layer; an intermediate layer interposed between the pinned and free ferromagnetic layers; and a pinned layer contacting the pinned ferromagnetic layer. The free ferromagnetic material layer is made of ferromagnetic lamination materials, including a cobalt-nickel-iron alloy layer and a cobalt-iron alloy layer arranged on the cobalt-nickel-iron alloy layer. Cobalt-nickel-iron alloy layers have now been demonstrated for the reliable establishment of uniaxial magnetic anisotropy in cobalt-iron alloy layers. In addition, the uniaxial magnetic anisotropy is reliably maintained in the ferromagnetic stacked material even if the thickness of the CoNi-Fe alloy layer as well as the Co-Fe alloy layer is reduced.

Description

Ferromagnetic laminate materials with reliable uniaxial anisotropy

technical field

The present invention relates to a magnetoresistive film comprising the following layers: a pinned ferromagnetic layer; a free ferromagnetic layer; an intermediate layer disposed between the pinned and free ferromagnetic layers; and a pin contacting the pinned ferromagnetic layer layers, such as antiferromagnetic layers.

Background technique

Magnetoresistive elements are commonly used to read information data from a magnetic recording disk in a magnetic recording medium drive or a storage device such as a hard disk drive (HDD). A magnetoresistance film such as a spin valve film is used in the magnetoresistance element. The resistance of the spin-valve film changes as the direction of magnetization in the free ferromagnetic layer changes. This change in resistance enables the discrimination of magnetic bit data on a magnetic recording disk.

Generally, the free ferromagnetic layer of a spin valve film includes a nickel-iron (NiFe) alloy layer and a cobalt-iron (CoFe) alloy layer stacked on the nickel-iron alloy layer. Stacking the nickel-iron alloy layers helps to establish the uniaxial magnetic anisotropy in the cobalt-iron alloy layer. The establishment of uniaxial magnetic anisotropy in the cobalt-iron alloy layer results in reliable rotation of the magnetization in the free ferromagnetic layer receiving the magnetic field from the magnetic recording disk. Magnetic bit data can be reliably identified in this way.

Higher density magnetic recording requires magnetoresistive elements to further increase output. The output of the magnetoresistive element depends on eg the thickness of the free ferromagnetic layer. Stacking a free ferromagnetic layer of smaller thickness can improve the output of the magnetoresistive element as desired. However, it is difficult to establish uniaxial anisotropy in the free ferromagnetic layer if the thickness of the NiFe alloy layer in the free ferromagnetic layer is reduced. Loss of uniaxial anisotropy often prevents reliable discrimination of magnetic bit data.

Contents of the invention

It is therefore an object of the present invention to provide a ferromagnetic laminate material capable of reliably establishing uniaxial anisotropy even if the thickness is reduced.

According to the present invention, a ferromagnetic lamination material is provided, comprising: a cobalt-nickel-iron alloy layer; and a cobalt-iron alloy layer arranged on the cobalt-nickel-iron alloy layer.

Cobalt-nickel-iron alloy layers have now been demonstrated to reliably establish uniaxial magnetic anisotropy in cobalt-iron alloy layers. In addition, uniaxial magnetic anisotropy can be reliably maintained in the ferromagnetic stack material even if the thickness of the cobalt-nickel-iron alloy layer as well as the cobalt-iron alloy layer is reduced.

The ferromagnetic stack material can be used as a free ferromagnetic layer in a magnetoresistive film designed to discriminate magnetic bit data on a magnetic recording disk in a magnetic recording media drive such as a hard disk drive (HDD). The magnetoresistive film may include, for example, a pinned ferromagnetic layer; a free ferromagnetic layer comprising the above-mentioned ferromagnetic stack materials; an intermediate layer interposed between the pinned and free ferromagnetic layers; and a contact pinned ferromagnetic layer. A pinned layer that pins the ferromagnetic layer. The interlayer can be conductive or insulating. The pinned layer can be an antiferromagnetic layer or a layer of a specific hard magnetic material.

Here, the cobalt-nickel-iron alloy layer contains x[atom%] of cobalt, y[atom%] of nickel, and z[atom%] of iron based on the following expression:

100=x+y+z

41≤x≤72

z=y+10

This type of cobalt-nickel-iron alloy layer reliably establishes uniaxial magnetic anisotropy in the free ferromagnetic layer even if the thickness of the free ferromagnetic layer is reduced. Similarly, the cobalt-nickel-iron alloy layer contains x[atom%] of cobalt, y[atom%] of nickel and z[atom%] of iron based on the following expression:

100=x+y+z

40≤x≤50

35≤z≤36

At this time, the thickness of the cobalt-iron alloy layer is set to be less than 1.0 [nm].

Specifically, it is preferable that the coercive force in the cobalt-nickel-iron alloy layer in the direction of easy magnetization is equal to or less than 800 [A/m]. Further, it is preferable that the ratio Hc _(hard) /Hc(easy) of the coercive force Hc _(hard) in the hard magnetization direction to the coercive force Hc _{(easy )} in the easy magnetization direction in the cobalt-nickel-iron alloy layer is equal to or less than 0.7. Furthermore, the cobalt-nickel-iron alloy layer preferably has a saturation magnetization BS equal to or greater than 1.7 [T]. When all three conditions are satisfied, the Co-Ni-Fe layer is very beneficial to further reduce the thickness of the free ferromagnetic layer.

It should be noted that the above-mentioned ferromagnetic laminate materials can be used for any purpose other than the free ferromagnetic layer in the magnetoresistive film.

Description of drawings

From the following description in conjunction with the preferred embodiments of the accompanying drawings, the above and other objects, features and advantages of the present invention will become apparent, wherein:

Fig. 1 schematically shows a plan view of the internal structure of a hard disk drive (HDD);

Fig. 2 schematically shows an enlarged perspective view of a structure of a floating magnetic head slider according to a specific example;

Figure 3 schematically shows a front view of a read/write electromagnetic transducer viewed on an air bearing surface;

4 is an enlarged plan view of a magnetoresistive (MR) readout element;

Fig. 5 schematically shows an enlarged front view of a spin valve membrane structure according to the present invention;

6A is a graph showing a BH characteristic of a spin valve film according to the first example of the embodiment;

FIG. 6B shows a graph of BH characteristics of a spin-valve film according to a comparative example;

Figure 7 shows a graph showing the relationship between the composition of cobalt-nickel-iron (CoNiFe) alloys and good magnetic properties;

8 is an enlarged plan view of a current perpendicular to the plane (CPP) structure MR readout element; and

Fig. 9 is an enlarged front view of a tunnel junction magnetoresistance (TMR) film.

Detailed ways

FIG. 1 schematically shows the internal structure of a hard disk drive (HDD) 11 as an example of a recording medium drive or storage device. The HDD 11 includes a box-shaped main housing 12 defining, for example, a flat parallelepiped internal space. In the inner space of the main casing 12 is introduced at least one magnetic recording disk 13 . The magnetic recording disk 13 is mounted on a drive shaft of a spindle motor 14 . The spindle motor 14 is capable of driving the magnetic recording disk 13 to rotate at a relatively high rotational speed, for example, in a range between 4,200 rpm and 7,200 rpm or 10,000 rpm. A cover, not shown, combines with the main housing 12 to define a closed interior space between the main housing 12 and itself.

The bracket 16 is also disposed within the inner space of the main housing 12 . The support 16 is designed to swing around the vertical support shaft 15 . The bracket 16 includes a rigid swing arm 17 extending in the horizontal direction of a vertical support shaft 15 , and an elastic head suspension 18 is fixed to the top end of the swing arm 17 . An elastic head suspension 18 extends forward from the swing arm 17 . Normally, the flying head slider 19 is suspended on the head suspension 18 by a gimbal spring not shown. The head suspension 18 is used to propel the flying head slider 19 toward the surface of the magnetic recording disk 13 . When the magnetic recording disk 13 rotates, the flying head slider 19 can receive an air flow generated along the rotating magnetic recording disk 13 . The air flow is used to generate a lift force on the flying head slider 19 . Higher stability is thereby established by the balance between the lifting force and the driving force of the head suspension 18, and the flying head slider 19 can be held on the surface of the magnetic recording disk 13 during the rotation of the magnetic recording disk 13 with this higher stability. float.

During the floating of the flying head slider 19 , when the drive bracket 16 is driven to swing around the support shaft 15 , the flying head slider 19 can traverse the recording tracks defined on the magnetic recording disk 13 in the radial direction of the magnetic recording disk 13 . This radial movement can place the flying head slider 19 exactly on the target recording track on the magnetic recording disk 13 . At this time, for example, an electromagnetic actuator 21 such as a voice coil motor (VCM) can be used to realize the swing of the bracket 16 . Generally, when two or more magnetic recording disks 13 are disposed within the inner space of the main housing 12 , a pair of elastic head suspensions 18 and swing arms 17 are disposed between adjacent magnetic recording disks 13 .

A specific example of the flying head slider 19 is shown in FIG. 2 . This type of flying head slider 19 includes a flat parallelepiped slider body 22 made of Al ₂ O ₃ —TiC, and a head protection layer 24 bonded to the tail of the slider body 22 or the slider-out end. The head protective layer 24 may be made of Al ₂ O ₃ . A read/write electromagnetic transducer 23 is embedded in the head protective layer 24 . A medium-facing surface or bottom surface 25 is defined in continuous extension on the slider 22 and the head protection layer 24, facing the surface of the magnetic recording disk 13 at a distance. Bottom surface 25 is designed to receive airflow 26 generated along the surface of rotating magnetic recording disk 13 .

A pair of rails 27 are formed on the bottom surface 25 extending from the leading or inflow end towards the tail or outflow end. Each rail 27 is designed to define an air bearing surface 28 on its top face. Specifically, the airflow 26 generates the aforementioned lift forces at each air bearing surface 28 . The read/write electromagnetic converter 23 embedded in the head protection layer 24 is designed to expose its front end on the air bearing surface 28, which will be described in detail later. A diamond-like carbon (DLC) protective layer may be additionally formed to extend on the air bearing surface 28 to cover the front end of the electromagnetic transducer 23 . Flying head slider 19 may take any shape or form other than those described above.

As shown in detail in FIG. 3, the electromagnetic transducer 23 forms a so-called composite type thin-film magnetic head. Specifically, the electromagnetic transducer 23 includes a magnetoresistive (MR) readout element 31 and a thin film magnetic or inductive write head 32 . MR read element 31 is designed to discriminate magnetic bit data in response to changes in resistance to an applied field from magnetic recording disk 13 . The thin film magnetic head 32 is designed to record magnetic bit data into the magnetic recording disk 13 by using a magnetic field induced by a conductive scroll coil pattern not shown.

The MR readout element 31 is located between the upper and non-magnetic gap layers 33,34. The upper and lower non-magnetic gap layers 33, 34 may be made of, for example, Al ₂ O ₃ (aluminum oxide). The upper and lower non-magnetic gap layers 33,34 inserted into the MR read element 31 are located between the upper and lower shield layers 35,36. The upper and lower shield layers 35, 36 may be made of FeN, NiFe, or the like. The lower shield layer 36 may extend on the surface of the Al ₂ O ₃ (aluminum oxide) layer 37 . The aluminum oxide layer 37 serves as the lower half layer of the above-mentioned head protective layer 24, ie, the backing layer.

The thin film magnetic head 32 includes a nonmagnetic gap layer 38 extending on the surface of the upper shield layer 35 . The non-magnetic gap layer 38 may be made of, for example, Al ₂ O ₃ (aluminum oxide). The upper magnetic pole layer 39 is opposed to the upper shield layer 35 . The non-magnetic gap layer 38 is disposed between the upper shield layer 35 and the upper magnetic pole layer 39 . Upper magnetic pole layer 39 may be made of, for example, NiFe. The upper magnetic pole layer 39 is covered by an Al ₂ O ₃ (aluminum oxide) layer 40 extending on the non-magnetic gap layer 38 . The aluminum oxide layer 40 is designed to interpose the MR read element 31 and the thin film magnetic head 32 between the above-mentioned aluminum oxide layer 37 and itself. Specifically, the aluminum oxide layer 40 is designed as the upper half layer of the head protective layer 24, ie, the outer cover layer.

The upper magnetic pole layer 39 and the upper shield layer 35 are used together to define the magnetic core of the thin film magnetic head 32 . Specifically, the upper shield layer 35 of the MR readout element 31 is designed to additionally function as the lower magnetic pole layer of the thin-film magnetic head 32 . When a magnetic field is induced in the conductive scroll pattern, magnetic flux is exchanged between the upper magnetic pole layer 39 and the upper shield layer 35 . The nonmagnetic gap layer 38 leaks the exchanged magnetic flux from the air bearing surface 28 . The magnetic flux thus leaked forms a magnetic field for recording, that is, a write gap magnetic field. The upper shield layer 35 of the MR read element 31 is determined by the lower magnetic pole layer of the thin film magnetic head 32 .

Referring also to FIG. 4 , the MR readout element 31 includes a magnetoresistive (MR) film, ie, a spin-valve film 41 extending along the air bearing surface 28 on the planar surface of the nonmagnetic gap layer 34 . A pair of end faces are defined on the spin valve film 41 so as to intersect the flat surface of the nonmagnetic gap layer 34 by an angle of inclination θ.

Similarly, a pair of magnetic domain control hard magnetic films 42 are formed extending along the air bearing surface 28 on the flat surface of the nonmagnetic gap layer 34 . The magnetic domain control hard magnetic film 42 is designed to insert the spin valve film 41 along the air bearing surface 28 on the flat surface of the nonmagnetic gap layer 34 . Front ends of the magnetic domain control hard magnetic films 42 are respectively connected to end faces of the spin valve films 41 . The magnetic domain control hard magnetic film 42 may be made of a hard magnetic material such as CoPt, CoCrPt, or the like.

The wiring layer 43 is formed to extend on the surface of the magnetic domain control hard magnetic film 42 . The wiring layer 43 is interposed between the magnetic domain control hard magnetic film 42 and the upper shield layer 35 . The lead or front end of the wiring layer 43 is connected to the end face of the spin valve film 41 through the magnetic domain control hard magnetic film 42 . A read current is supplied to the spin valve film 41 through the wiring layer 43 . The lead layer 43 can be made of a material with higher conductivity, such as Cu.

As shown in FIG. 4 , the lead layer 43 is designed such that the front end exposed from the air bearing surface 28 extends rearward along the flat surface of the non-magnetic gap layer 34 . The terminal pads 44 are respectively connected to the rear ends of the lead layers 43 . The terminal pad 44 may extend on the surface of the lead layer 43 . When the flying head slider 19 is fixed on the elastic head suspension 18, the terminal pads 44 are connected to unshown terminal pads on the elastic head suspension 18 through, for example, Au balls, not shown.

As shown in FIG. 5 , the spin valve film 41 includes a base layer 51 provided on the surface of the nonmagnetic gap layer 34 . The base layer 51 may be made of, for example, a nickel-chromium (NiCr) alloy layer.

The pinning layer 52 is provided on the surface of the base layer 51 . The pinning layer 52 may be made of an antiferromagnetic alloy material such as PdPtMn, FeMn, or the like. In addition, the pinning layer 52 may be made of a hard magnetic material. The pinned ferromagnetic layer 53 is disposed on the surface of the pinned layer 52 . The pinned ferromagnetic layer 53 includes first, second and third cobalt-iron (CoFe) alloy ferromagnetic layers 53 a , 53 b , 53 c sequentially stacked on the surface of the pinned layer 52 . A ruthenium (Ru) bonding layer 54 is interposed between the first and second CoFe alloy ferromagnetic layers 53a, 53b. A reflective film or oxide layer 55 is interposed between the second and third CoFe alloy ferromagnetic layers 53b, 53c. In addition, the pinned ferromagnetic layer 53 may have structures other than those described above. The pinning layer 52 serves to fix the magnetization in the pinned ferromagnetic layer 53 in a predetermined direction.

The nonmagnetic intermediate layer 56 is provided on the surface of the pinned ferromagnetic layer 53 . The nonmagnetic interlayer 56 may be made of a conductive material such as Cu. A free ferromagnetic layer 57 is provided on the surface of the nonmagnetic intermediate layer 56 . The free ferromagnetic layer 57 includes a cobalt-iron (CoFe) alloy layer 57a extending on the surface of the nonmagnetic intermediate layer 56, and a cobalt-nickel-iron (CoNiFe) alloy layer 57b extending on the cobalt-iron alloy layer 57a. The surface of the free ferromagnetic layer 57 is covered with a protective layer 58 . The protective layer 58 includes a copper (Cu) layer 58a and a cap or tantalum (Ta) layer 58b disposed on the upper surface of the Cu layer 58a.

When the MR readout element 31 is opposed to the magnetic recording disk 13 for reading magnetic information data, the magnetization of the free ferromagnetic layer 57 can rotate in the spin valve film 41 in response to magnetic polarity reversal applied by the magnetic recording disk 13 . The rotation of the magnetization in the free ferromagnetic layer 57 results in a change in electrical resistance in the spin valve film 41 . When a read current is applied to the spin valve film 41 through the wiring layer 43 , a change in the magnitude of any parameter such as voltage appears in the read current output output from the terminal pad 44 in response to a change in magnetoresistance. The size variation can be used to distinguish the magnetic bit data recorded on the magnetic recording disk 13 .

At this time, the above-mentioned cobalt-nickel-iron alloy layer 57 b is used to reliably determine the uniaxial magnetic anisotropy in the free ferromagnetic layer 57 in the spin valve film 41 . When a magnetic field is applied to the free ferromagnetic layer 57 by the magnetic recording disk, the establishment of uniaxial magnetic anisotropy results in reliable rotation of the magnetization in the free ferromagnetic layer 57 . Magnetic bit data can be reliably discriminated. Furthermore, even if the thicknesses of the cobalt-iron alloy layer 57 a and the cobalt-inconel alloy layer 57 b are reduced, uniaxial magnetic anisotropy can be reliably determined in the free ferromagnetic layer 57 . The spin-valve film 41 exhibits a large resistance change, and thus the output voltage of the terminal pad 44 has a large amplitude change. In this way an increased output can be obtained.

The present inventors have observed the above-mentioned characteristics of the spin-valve film 41 . During the observation, the inventors deposited stacked materials on a wafer in a vacuum atmosphere. The laminated material sequentially includes NiCr with a thickness of about 6.0nm, a PdPtMn layer with a thickness of about 15.0nm, a first CoFe alloy ferromagnetic layer 53a with a thickness of about 1.5nm, a Ru bonding layer 54 with a thickness of about 0.85nm, and a PdPtMn layer with a thickness of about 1.0nm. The second CoFe alloy ferromagnetic layer 53b. The layered material is deposited using sputtering. After the deposition of the second CoFe alloy ferromagnetic layer 53b, oxygen gas was introduced into the vacuum atmosphere. The introduction of oxygen was maintained for 70 seconds. The introduced oxygen is used to form an oxide layer 55 on the surface of the second CoFe alloy ferromagnetic layer 53b. The vacuum atmosphere is formed again after the oxide layer 55 is formed. The inventors subsequently sequentially deposited on the wafer a third CoFe alloy ferromagnetic layer 53c with a thickness of 1.5nm, a Cu layer with a thickness of about 2.1nm, a cobalt-iron alloy layer 57a with a thickness of about 0.5nm, and a cobalt-nickel-iron alloy layer 57b with a thickness of about 1.7nm , a Cu layer with a thickness of about 1.2 nm, and a tantalum layer with a thickness of about 3.0 nm. Sputtering can also be used for deposition. Co ₉₀ Fe ₁₀ alloy (atom%) is used for the CoFe alloy ferromagnetic layers 53a, 53b, 53c, 57a. Co ₄₁ Fe ₂₄ Ni ₃₅ alloy (atom%) is used as the CoNiFe alloy ferromagnetic layer. After the deposition is completed, the PdPtMn layer is adjusted on the basis of heat treatment. In this way, the spin-valve film 41 of the first example was prepared. The inventors measured the magnetoresistance (MR) ratio [%], surface resistance ρ/t[Ω], resistance change Δρ/t[Ω], magnetic coupling field Hin [A/m] of the prepared spin valve film 41 and the magnetic coupling or pinning field Hua [kA/m].

The present inventors also prepared spin-valve membranes of comparative examples. The spin-valve film was formed in the above-mentioned manner except that the CoFe alloy layer 57a and the CoFe alloy layer 57b were replaced by a combination of a CoFe alloy layer having a thickness of about 1.0 nm and a NiFe layer having a thickness of about 2.0 nm in the free ferromagnetic layer 57. . After adjusting the PdPtMn layer on the basis of heat treatment, the inventors measured the magnetoresistance (MR) ratio [%], surface resistance ρ/t[Ω], resistance change Δρ/t[Ω] of the spin-valve film of the comparative example , the magnetic coupling field Hin [A/m] and the magnetic coupling or pinning field Hua [kA/m].

[Table 1] MR ratio [%] Δρ/t[Ω] ρ/t[Ω] Hin[A/m] Hua[kA/m] example 1 12.2 2.22 18.1 294.4 113.8 Comparative example 1 11.5 1.81 15.8 748.0 131.3

As can be seen from Table 1, the MR ratio in the spin-valve film 41 of the first example is significantly improved as compared with the spin-valve film of the comparative example. The spin-valve film 41 of the first example exhibits a large resistance change amplitude Δρ/t. Furthermore, as shown in FIG. 6A , uniaxial magnetic anisotropy in the spin-valve film 41 of the first example was confirmed regardless of thickness reduction. On the other hand, uniaxial magnetic anisotropy loss can be observed in the spin-valve film shown in Fig. 6B.

The present inventors similarly prepared the spin-valve film of the second example. The inventors again deposited the laminated material on the wafer in a vacuum atmosphere. The stacked material sequentially includes a NiCr layer with a thickness of about 6.0nm, a PdPtMn layer with a thickness of about 15.0nm, a first CoFe alloy ferromagnetic layer 53a with a thickness of about 1.2nm, a Ru bonding layer 54 with a thickness of about 0.85nm, and a second layer with a thickness of about 1.2nm. Two CoFe alloy ferromagnetic layers 53b. The layered material is deposited using sputtering. Oxygen was introduced into the vacuum atmosphere after depositing the second CoFe alloy ferromagnetic layer 53b. The introduction of oxygen is maintained for 90 seconds. The introduced oxygen is used to form an oxide layer 55 on the surface of the second CoFe alloy ferromagnetic layer 53b. The vacuum atmosphere is formed again after the oxide layer 55 is formed. The present inventor then sequentially deposited on the wafer a third CoFe alloy ferromagnetic layer 53c with a thickness of 1.7nm, a Cu layer with a thickness of about 2.1nm, a cobalt-iron alloy layer 57a with a thickness of about 0.5nm, a CoNiFe alloy layer 57b with a thickness of about 1.7nm, Au layer with a thickness of about 0.6 nm. Sputtering can also be used for deposition. Co ₆₀ Fe ₄₀ alloy (atom%) is used for the CoFe alloy ferromagnetic layers 53a, 53b, 53c, 57a. Co ₄₁ Fe ₂₄ Ni ₃₅ alloy (atom%) is used for the CoNiFe alloy ferromagnetic layer 57b. After the deposition is completed, the PdPtMn layer is adjusted on the basis of heat treatment. In this way, the spin-valve film 41 of the second example was prepared. The inventors measured the magnetoresistance (MR) ratio [%], surface resistance ρ/t[Ω], resistance change Δρ/t[Ω], magnetic coupling field Hin [A/m] of the prepared spin valve film 41 and the magnetic coupling or pinning field Hua [kA/m].

The present inventors also prepared spin-valve films of comparative examples in the above-mentioned manner. The spin-valve film was formed in the above-mentioned manner except that the cobalt-iron alloy layer 57a and the cobalt-nickel-iron alloy layer 57b were replaced by a combination of a CoFe alloy layer with a thickness of about 1.0 nm and a NiFe layer with a thickness of about 2.0 nm in the free ferromagnetic layer 57. . After adjusting the PdPtMn layer on the basis of heat treatment, the inventors measured the magnetoresistance (MR) ratio [%], surface resistance ρ/t[Ω], resistance change Δρ/t[Ω] of the spin-valve film of the comparative example , the magnetic coupling field Hin [A/m] and the magnetic coupling or pinning field Hua [kA/m].

[Table 2]

MR ratio [%] Δρ/t[Ω] ρ/t[Ω] Hin[A/m] Hua[kA/m] Example 2 15.5 2.60 16.7 262.6 98.7 Comparative example 2 14.4 2.32 16.2 803.7 81.2

As can be seen from Table 2, the MR ratio in the spin-valve film 41 of the second example is significantly improved compared with the spin-valve film of the comparative example. The spin-valve film 41 of the second example exhibits a larger resistance change amplitude Δρ/t. In addition, uniaxial magnetic anisotropy in the spin-valve film 41 of the second example was confirmed regardless of thickness reduction.

The present inventors observed the magnetic properties of the CoNiFe alloy layer 57b. The present inventors measured the saturation magnetic density Bs [T], the coercive force Hc _(easy) [A/m] in the direction of easy magnetization, and the coercive force Hc _(hard) [A/m] of various compositions of CoNiFe alloy layers. /m]. As shown in Table 3, uniaxial anisotropy was observed in the CoNiFe alloy layers of specific compositions.

[table 3]

Composition [at%] Bs[T] Hc _(easy) [A/m] Hc _(hard) [A/m] Co ₇₂ Ni ₉ Fe ₁₉ 1.78 748.0 0.70 Co ₆₃ Ni ₁₃ Fe ₂₄ 1.81 843.5 0.74 Co ₅₄ Ni ₁₈ Fe ₂₈ 1.85 851.5 0.75 Co ₄₈ Ni ₁₆ Fe ₃₆ 1.75 819.6 0.72 Co ₄₆ Ni ₁₉ Fe ₃₅ 1.79 859.4 0.76 Co ₄₂ Ni ₂₃ Fe ₃₅ 1.72 756.0 0.68 Co ₄₁ Ni ₂₄ Fe ₃₅ 1.75 342.2 0.52

The composition of the CoNiFe alloy layer can be determined according to the structure shown in FIG. 7 to determine the uniaxial anisotropy. Specifically, the CoNiFe layer should contain cobalt in x[atom%], nickel in y[atom%] and iron in z[atom%] based on the following expressions:

100=x+y+z

41≤x≤72

z=y+10

In addition, the CoNiFe layer contains x[atom%] of cobalt, y[atom%] of nickel, and z[atom%] of iron based on the following expressions:

100=x+y+z

40≤x≤50

35≤z≤36

It should be noted that a margin of ±2 [atom%] is acceptable in the composition of the CoNiFe alloy. Specifically, the thickness of the free ferromagnetic layer 57 can be reduced under the following conditions: the coercivity of the CoNiFe alloy layer in the direction of easy magnetization is equal to or less than 800 [A/m], and/or the cobalt-nickel-iron alloy layer is provided The ratio of the coercive force Hc _(hard) in the hard magnetization direction to the coercive force Hc _(easy) in the easy magnetization direction is equal to or less than 0.7, and/or the CoNiFe alloy layer has a saturation magnetization equal to or greater than 1.7 [T], for example Strength Bs.

As shown in FIG. 8, a spin valve film 41 is provided in, for example, a so-called current perpendicular to plane (CPP) structure MR readout element 31a. The spin valve film 41 is based on a CPP structure between the upper and lower electrode layers 43a, 43b of the MR readout element 31a. The spin valve film 41 can only have the above-mentioned structure. At this time, if the electrode layers 43a, 43b are made of a conductive magnetic material, the electrode layers 43a, 43b can additionally function as upper and lower shield layers of the CPP structure MR readout element 31a. Furthermore, like reference numerals pertain to structures or components equivalent to the above-mentioned MR readout element 31 . The reduced thickness of the free ferromagnetic layer 57 results in a reduced space between the upper and lower shield layers of the CPP structure MR readout element 31a. The linear resolution of the magnetic recording can thereby be improved along the recording track of the magnetic recording disk 13 .

The above-mentioned spin valve film 41 may be replaced with a tunnel junction magnetoresistance (TMR) film in the CPP structure MR readout element 31a. As shown in FIG. 9, the above-described free ferromagnetic layer 57 may be provided on, for example, the TMR film 41b. An insulating nonmagnetic interlayer 61 is provided instead of the conductive nonmagnetic interlayer 56 in the above-mentioned TMR film 41b. In addition, like reference numerals belong to structures or components equivalent to the above-mentioned spin valve film 41 . If the free ferromagnetic layer 57 is provided in the TMR film 41b in this way, the reduced thickness of the free ferromagnetic layer 57 as described above results in a reduced space between the upper and lower shield layers of the CPP structure MR readout element 31a. The linear resolution of the magnetic recording can thereby be improved along the recording track of the magnetic recording disk 13 .

It should be noted that the spin valve film 41 and the TMR film 41 b may be formed to include the free ferromagnetic layer 57 under the pinned ferromagnetic layer 53 .

Claims (18)

1. A magnetoresistance film, comprising: pinned ferromagnetic layer; A free ferromagnetic layer made of a cobalt-nickel-iron alloy layer and a cobalt-iron alloy layer; an intermediate layer disposed between the pinned and free ferromagnetic layers; and The pinned layer contacts the pinned ferromagnetic layer. 2. The magnetoresistance film according to claim 1, wherein said intermediate layer is made of a conductive material. 3. The magnetoresistive film according to claim 2, wherein said pinned layer may be an antiferromagnetic layer. 4. The magnetoresistance film according to claim 3, wherein the coercive force in the direction of easy magnetization in the cobalt-nickel-iron alloy layer is equal to or less than 800 A/m. 5. The magnetoresistance film according to claim 4, wherein the ratio Hc (hard) of coercive force Hc _(hard) in the direction of hard magnetization to the coercive force Hc _{(easy) in} the direction of easy magnetization in the cobalt-nickel-iron alloy layer Hc _(easy) is equal to or less than 0.7. 6. The magnetoresistance film according to claim 5, wherein the cobalt-nickel-iron alloy layer has a saturation magnetization Bs equal to or greater than 1.7T. 7. The magnetoresistive film according to claim 6, wherein the cobalt-nickel-iron alloy layer contains x atom % of cobalt, y atom % of nickel and z atom % of iron based on the following expression: 100=x+y+z 41≤x≤72 z=y+10 8. The magnetoresistance film according to claim 7, wherein the thickness of the cobalt-iron alloy layer is set to be less than 1.0 nm. 9. The magnetoresistive film according to claim 6, wherein the cobalt-nickel-iron alloy layer contains x atom % of cobalt, y atom % of nickel and z atom % of iron based on the following expression: 100=x+y+z 40≤x≤50 35≤z≤36 10. The magnetoresistance film according to claim 9, wherein the thickness of the cobalt-iron alloy layer is set to be less than 1.0 nm. 11. A ferromagnetic laminated material comprising: a cobalt-nickel-iron alloy layer; and A cobalt-iron alloy layer disposed on the cobalt-nickel-iron alloy layer. 12. The ferromagnetic laminated material according to claim 11, wherein the coercive force in the direction of easy magnetization in the cobalt-nickel-iron alloy layer is equal to or less than 800 A/m. 13. The ferromagnetic laminated material according to claim 12, wherein the ratio Hc ₍ hard) of the coercive force Hc _(hard) in the direction of hard magnetization to the coercive force Hc _(easy) in the direction of easy magnetization in the cobalt-nickel-iron alloy layer ₎ /Hc _(easy) is equal to or less than 0.7. 14. The ferromagnetic laminated material according to claim 13, wherein the cobalt-nickel-iron alloy layer has a saturation magnetization Bs equal to or greater than 1.7T. 15. The ferromagnetic laminate material according to claim 14, wherein the cobalt-nickel-iron alloy layer contains x atom % of cobalt, y atom % of nickel and z atom % of iron based on the following expression: 100=x+y+z 41≤x≤72 z=y+10 16. The ferromagnetic laminated material according to claim 15, wherein the thickness of the cobalt-iron alloy layer is set to be less than 1.0 nm. 17. The ferromagnetic laminate material according to claim 14, wherein the cobalt-nickel-iron alloy layer contains x atom % of cobalt, y atom % of nickel and z atom % of iron based on the following expression: 100=x+y+z 40≤x≤50 35≤z≤36 18. The ferromagnetic laminated material according to claim 17, wherein the thickness of the cobalt-iron alloy layer is set to be less than 1.0 nm.

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